1. Field of the Invention
This invention relates generally to grain combines, and in particular, to an improved threshing assembly for a combine.
2. Description of the Prior Art
A grain combine threshing section has two primary parts. These are the threshing rotor and cage. The threshing rotor rotates within the threshing cage and has rasp bars mounted on its outer surface. The threshing cage is perforated and may rotate along with the threshing rotor, but at slower speed. Steel vanes are mounted to the interior surface of the threshing cage. Crop is introduced into the space between the threshing rotor and the threshing cage. As material passes between the threshing rotor and cage, the rasp bars provide agitation and shear to separate the grain from the remainder of the crop. The threshed grain passes through the perforations of the threshing cage so that it can be collected.
For effective threshing, the clearance between the rasp bars of the threshing rotor and the interior of the threshing cage are set according to the type of crop being threshed. Decreasing the clearance between the rasp bars and threshing cage can improve threshing. Yet if this clearance is too small, grain damage can occur. Therefore, larger grains require greater clearances between the rasp bars and the threshing concave, where the crop is threshed. Because of this, the threshing assembly or its components has to be adjusted to provide the necessary clearances for the type of crop being harvested. This is undesireable due to the labor and time required to modify the threshing assembly.
What is therefore needed is a threshing assembly that can accommodate crops of different grain sizes without the necessity of adjusting of the threshing assembly.